Reference plane for paving machines



July 5, 1936 n. R. DAVIN 3,259,034

REFERENCE PLANE FOR PAVING MACHINES Filed April 15, 1963 Fig.l.

INVENTOR Donald R. Davin United States Patent 3,259,034 REFERENCE PLANE FOR PAVING MACHINES Donald R. Davin, Shelbyville, 111., assignor to Blaw-Knox Company, Pittsburgh, Pa., a corporation of Delaware Filed Apr. 15, 1963, Ser. No. 273,105 8 Claims. (Cl. 9446) This invention relates to apparatus for establishing a reference plane for the leveling mechanism of a pavement laying machine.

The use of paving machines to mechanically place and level paving material is old and well-known. Such pavers typically comprise apparatus to place the paving material, and a screed to level or strike-off the material placed in front of it. When the material being placed is bituminous concrete, a paver customarily consists of a tractor unit to supply power and provide traction, a supply hopper to receive raw material, conveyors on the tractor to distribute and position the material, and a screed positioned adjacent the rear end of the tractor to strike off and smooth the distributed bituminous material. The provision of adjusting means of some sort to regulate the screed position is quite old. Various means have been employed to maintain a proper screed adjustment and thereby secure a smooth and regular pavement surface free of undulations. One form of screed adjusting apparatus and of means for controlling the adjustment of that apparatus is shown in copending Ackerrnan et al. application Serial No. 821,561, filed June 19, 1959. That application discloses a gauge or feeler which gauges a distance from a part of the screed structure to a predetermined reference plane. The reference plane may be a wire or the like placed by a survey crew whereby the final surface of the pavement will likewise be level and of uniform slope. Alternatively, the reference plane may be a parallel course of previously laid paving material.

In the placing of bituminous material to form a highway or the like, it is customary to form a sub grade upon which the paver advances and upon which the paving material is placed. If the material being placed is to form the base course, then the graded earth or the aggregate placed thereon for drainage will constitute the sub grade. In like manner, the base course will, when placed, constitute the sub grade for the finish course of line aggregate to be placed on top of it.

I have invented new and useful apparatus for forming a predetermined reference plane for use with pavers. I provide beam means adapted to extend alongside the paver extending in the direction of travel of the paver. I provide a plurality of beam support means at spaced intervals along the beam and mount them for vertical yielding movement relative to the beam. I preferably provide a beam member of substantial length having a surface constituting a reference plane. I prefer to mount numerous foot means at evenly spaced intervals along the beam and to support the beam therefrom. I further preferably provide yielding means intermediate each foot means and the beam member, said yielding urging the foot means downwardly in relation to the beam member. I prefer to provide skid means at the lower end of each foot member whereby each foot member and the entire structure can be skidded along the sub grade. I further prefer to provide means connecting the paver and the beam means for concurrent advance of the beam means with the paver.

I prefer to provide a beam structure which is at least as long as the paver, a longer 'beam being employed Where it is practicable to do so. I prefer that the foot members be spaced over a distance at least as great as the wheelbase of the paver whereby any irregularities which cause pitching of the paver will be minimized by the greater length of the beam structure.

3,259,634 Patented July 5, 1966 Other details, objects, and advantages of my invention will become apparent as the following description of a present preferred embodiment thereof proceeds.

In the accompanying drawings, I have shown a present preferred embodiment of my invention in which FIGURE 1 is a side elevational view of a paver being used in conjunction with a reference plane constructed in accordance with my invention; and

FIGURE 2 is a detail view of the beam structure and one of the foot members shown in FIGURE 1, with some portions of the drawing being shown in section.

A paver 1 is shown in FIGURE 1. It comprises a hopper 2 at the forward end adapted to receive bituminous material f-rom trucks and a distributing screw 3 at the rear end to distribute bituminous material across the width of the sub grade. Conveyors (not illustrated) are provided to dump bituminous material from hopper 2 in front of screw 3. A screed 4 is attached to a screed arm 5 extending forwardly on each side of the paver from screed 4. The screed extends transversely across the rear of the paver. The forward end of each screed arm 5 is attached to the paver in a'vertically slidable pivoted connection and may be raised or lowered by a hydraulic cylinder and piston 6. The paver is mounted upon wheels 7, which ride upon a sub grade 8, upon which it is working. The sub grade is intended to mean the surface which is to receive the material being laid by the paver, whether that constitutes an earlier laid course of bituminous material, or graded earth, or a layer of aggregate placed on the earth. The newly placed course of material 9 is laid behind the paver.

In the operation of the paver, the elevation at the top surface of the new pavement course 9 and consequently its thickness, are controlled by adjusting the angle of the screed bottom to another plane. If the forward end of the screed arm 5 is raised, screed 4 will gradually climb a slope until it levels off under its own action forming a thicker mat. Lowering the front end of the screed arms will produce exactly the opposite effect and will result in the production of a thinner mat. The same results may optionally be obtained by pivotally mounting screed 4 upon screed arms 5 and pivotally shifting the screed on the screed arms while holding the front ends of the screed arms in fixed position.

It has been common practice to control the screed angle by manual adjustment. More recently it has been proposed to employ a gauge or sensor which will continuously measure the angle of the screed to a reference plane and automatically modify the adjustment as necessary to maintain a constant angle between the screed and a reference plane. Such apparatus is described in Ackerman et a1. application Serial No. 821,561. In the paver shown in FIGURE 1, a feeler 10 is pivoted at 11 and is mounted upon a bracket 12, positioned to the forward end of screed arm 5. The feeler feels or contacts a reference plane which is at a predetermined position. That is to say the reference plane is established independently of the paver and is at a position which controls the paver. The position of the reference plane is established prior to the time that the paver is active at any given point. Feeler 10 is in controlling relationship to the screed angle by connecting through a control mechanism to hydraulic cylinder 6 Whose operation it controls. The sensor mechanism comprising the feeler and control mechanism causes the screed arms to follow the reference plane independently of any motion of the paver, thereby maintaining the uniform and steady angular relationship between the screed and the reference plane.

A beam 13 is provided extending horizontally alongside the paver in the direction of its movement. Beam 13 is preferably a fabricated structure which is hollow and of light weight. A series of foot members 14- are evenly spaced along the length of the beam. One of the foot members is shown in detail in FIGURE 2. It comprises a rod terminating in a bracket 16. A boss 17 is formed in the upper part of beam 13 and has a bushing 18 fitted in it. The inner surface of bushing 18 is spherical and receives a spherical washer 19, in which rod 15 is slidably mounted. Flat washer 20 is positioned on rod 15 beneath spherical washer 19. The rod extends downwardly below washer 20 through holes 21 and 22, which are large enough to provide adequate clearance around rod 15. A bracket 23 is welded to the lower surface of beam 13, forward of rod 15. A link 24 is pivoted to bracket 23 at pivot 25 and is pivoted to bracket 16 at pivot 26. A spring 27 is in compression between washer 2i and a shoulder 28 of bracket 16 and is continually effective to urge rod 15 and bracket 16 downwardly. A skid 29 is pivoted to bracket 16 at pivot 3t It has upwardly turned ends 31 for sliding along a sub grade.

Each of the foot members 14 is of like construction. The springs 27 are of such force that they collectively carry the weight of beam 13, but each of them is so weak that compression of any one will not exert any substantial force upon the beam relative to its weight.

A bracket 32 is welded to the upper surface of beam 13 and has a drag link 33 pivoted to it. The other end of drag link 33 is connected to a bracket on the front end of the paver at a pivot 34. An upwardly extending bracket 35 is attached to the beam at its mid point by clamps 36. The upper end of bracket 35 fits within a slot in bracket 12 to restrain the beam against lateral horizontal movement relative to the paver while leaving it free to move vertically.

In operation, the paver advances along sub grade 8. Paving material is deposited in hopper 2 and is spread by the paver in the usual manner with the screed striking off the paving material and smoothing it into a mat. As paver 1 moves forward, drag link 33 pulls beam 13 forward. It is maintained in generally parallel relationship with paver 1 by the engagement of brackets 12 and 35. The beam is carried by foot members 14, and provides a predetermined reference plane which is substantially parallel to the sub grade. The weight of the beam is carried by all of the springs 27, which are compressed by the beam until the summation of the spring forces equals the weight of the beam. As the beam is advanced by the pull of drag link 33, skids 29 slide along the sub grade. As an irregularity is reached by the first skid, it is forced upwardly against the associated spring 27. Since there are numerous foot members, that one spring 27 will exert relatively small force when compressed by upward movement of the skid as compared with the weight of the beam. If twelve foot members are provided, as illustrated in FIGURE 1, each foot member will carry only one-twelfth of the total weight of the beam and the raising of the associated skid by passing over an obstruction or irregularity will cause the beam to be raised a very small fraction of the distance which the skid is raised. It will be apparent, therefore, that as the paver advances and advances the beam with it that the beam will maintain a position substantially parallel to the sub-grade and substantially independently of irregularities and the like in the sub grade. The beam thus assumes a predetermined position and establishes a reference plane independently of pitches and variations in the height of the paver. The beam is of substantially greater length than the paver itself and is of even greater length than the wheel base of the paver. In this manner, irregularities in the sub-grade which are of sufficient size that the paver is caused by them to change its position are effectively reduced or eliminated.

Feeler 10 contacts the upper surface of beam 13 which constitutes a reference plane for the paver. Despite pitching of the paver as it passes over irregularities feeler 10 and the associated control mechanism maintain screed 4 in fixed angular relationship to the reference plane. If a wheel of the paver rises in passing over an irregularity or drops into a hole, feeler 10 will immediately rise or fall with the paver. It will immediately correct for the movement by causing cylinder 6 to shift the forward end of screed arm 5 until it is again in the desired relationship to beam 13. In this manner the screed is maintained in a desired attitude by reason of reference to the reference plane determined by beam 13.

While I have illustrated and described a present preferred embodiment of my invention, it is to be distinctly understood that I do not limit myself thereto and that my invention may be otherwise variously practiced within the scope of the following claims.

I claim:

1. An artificial reference plane for a paving machine comprising elongated horizontally extending beam means, a plurality of beam support .means extending vertically in slidable relation to said beam means, and yielding means intermediate the beam means and the beam support means, said yielding means urging said support means downwardly and said beam means upwardly.

2. An artificial reference plane for use with a paving machine comprising elongated horizontally extending beam means adapted to be coupled to the paving machine along the side of the paving machine, a plurality of foot means arranged for sliding movement along a sub grade upon which the paving machine is working, and carrying the beam means, said foo-t means being in vertically movable relationship to said beam means, and yielding means urging said foot means downward-1y and said beam means upwardly.

3. Means for forming a continuously effective reference plane fora paving machine working upon a sub grade comprising beam means positioned alongside the paving machine and extending in the direction of travel thereof, numerous spaced foot members vertically slidably connected to the beam means, and yielding means urging said foot members downwardly whereby the beam means is supported on the sub grade by said foot members acting through said yielding means.

4. A continuously effective reference plane for a paving machine working upon a sub grade comprising beam means having a surface which constitutes the reference plane, said beam means positioned along-side the paving machine and extending in the direction of travel thereof, a plurality of spaced foot members connected to the beam member for vertical slidable movement relative thereto, yielding means urging said foot members downwardly and supporting said beam means, and means connecting the paving machine and said beam means whereby forward movement of said paving machine advances the beam means.

5. A continuously effective reference plane lfor a paving machine working upon a sub grade comprising beam means having a surface adapted to receive gauge means mounted upon said paving machine, a plurality of foot means adapted to slide over the sub grade and disposed in vertically slidable relationship to the beam means at substantially regular intervals along the length of the beam means, yielding means for each of said foot means urging the associated foot means downwardly relative to the beam means and supporting the beam means, means connecting said beam means and the pavin machine with the beam means positioned along the side of the paving machine and extending in the direction of travel thereof whereby forward movement of the paving machine effects forward movement Otf the beam means.

6. An artificial reference plane for a paving machine working on a sub grade comprising an elongated horizontally extending beam having an effective length at least as great as substantially the length of the paving machine, a plurality of vertically extending foot members positioned in the beam for vertical movement relative thereto, said foot members being in spaced relationship along the length of the beam, yielding means associated with each foot member intermediate the beam and the foot member and urging the foot member downwardly relative to the beam.

7. An artificial reference plane :for a paving machine working on a sub grade comprising an elongated horizontally extending beam having a length at least as great as the length of the paving machine, a plurality of vertical foot membens arranged in vertically sliding relationship in the beam, said foot members being in evenly spaced relationship extending substantially from end to end of the beam, yielding means associated with each foot member and urging the foot memberdown and the beam up.

8. An artificial reference plane for a paving machine Working on a sub base comprising an elongated horizontally extending beam structure having a length greater than the length of the paving machine, numerous skid members having a configuration adapted to slide along said sub grade and evenly spaced along a substantial part of the length of said beam structure, slide members con nected to said skid members and arranged for vertical sliding movement in said beam structure, and yielding means urging said slide members and skid members downwardly and said beam structure upwardly.

References Cited by the Examiner UNITED STATES PATENTS 2,169,987 8/1939 Mosel 9446 2,295,519 9/ 1942 Millikin 94--46 2,491,275 12/ 1949 Millikin 9446 2,589,256 3/1952 Horning 94--46 2,591,502 4/1952 Bohannan 94-46 2,720,716 10/ 1965 White.

3,111,070 ll/1963 Pollitz 9446 FOREIGN PATENTS 1,056,865 10/1953 France.

CHARLES E. OCONNELL, Primary Examiner.

HENRY C. SUTHERLAND, Examiner.

20 N. C. BYERS, Assistant Examiner. 

4. A CONTINUOUSLY EFFECTIVE REFERENCE PLANE FOR A PAVING MACHINE WORKING UPON A SUB GRADE COMPRISING BEAM MEANS HAVING A SURFACE WHICH CONSTITUTES THE REFERENCE PLANE, SAID BEAM MEANS POSITIONED ALONGSIDE THE PAVING MACHINE AND EXTENDING IN THE DIRECTION OF TRAVEL THEREOF, A PLURALITY OF SPACED FOOT MEMBERS CONNECTED TO THE BEAM MEMBER FOR VERTICAL SLIDABLE MOVEMENT RELATIVE THERETO, YIELDING MEANS URGING SAID FOOT MEMBERS DOWNWARDLY AND SUPPORTING SAID BEAM MEANS, AND MEANS CONNECTING THE PAVING MACHINE AND SAID BEAM MEANS WHEREBY FORWARD MOVEMENT OF SAID PAVING MACHINE ADVANCES THE BEAM MEANS. 